1. Field of the Invention
This invention relates to a socket for mounting electric parts, and particularly to a mechanism for establishing a contacting state and a noncontacting state in a socket for electric parts such as an IC socket, etc., and more particularly to a mechanism for moving a plate mounted on a socket body adapted to establish the contacting state and noncontacting state.
2. Brief Description of the Prior Art
Japanese Utility Model Laid-open Publication No. Sho 57-175388 discloses means for realizing a contacting relation and a noncontacting relation by horizontally moving a plate along an upper surface of a socket body. This means includes respective pins projecting sidewards from the moving plate and socket body. When the moving plate is placed on the socket body, the pins of the moving plate and the pins of the socket body are aligned in a vertical relation. The means further includes an operating lever provided at one end portion thereof with a U-shaped groove which allows the pins of the moving plate and socket body to be removably inserted therein. In order to establish the contacting relation and the noncontacting relation, the lever, which extends upright astride the socket body, is pivoted in the horizontal direction so that a horizontal force is applied to the pins of the moving plate.
U.S. Pat. No. 4,750,891 attempts to effect the horizontal movement of the moving plate by pivoting a crank lever interposed between the moving plate and the socket body so that an eccentric portion of a crank shaft of the lever acts on the moving plate.
However, in the first mentioned prior art, the operating lever, which extends upright astride the socket body, becomes an obstacle when an electric part such as an IC is mounted or removed. Therefore, there is such an inconvenience in that the operating lever must be mounted or removed every time the moving plate is to be moved or the IC is to be mounted or removed. Moreover, it is necessary to always keep the operating lever nearby which is bothersome.
Furthermore, because the operating lever, which extends upright astride the socket body, is pivoted by a force acting in the horizontal direction in order to move the moving plate, it is practically impossible to pivot the operating lever by simply moving a manipulator of a robot in a vertical direction. Therefore, this prior art is not suitable for automating the moving operation of the moving plate.
In the second mentioned crank lever system, twisting of the crank shaft interposed between the socket body and the moving plate and motion is often not transmitted to the eccentric portion correctly. As a consequence, the moving distance of the moving plate is not constant and an insufficient contacting state can arise.
If the eccentric portion is enlarged to obtain a longer eccentric dimension of the crank shaft in order to in turn obtain a sufficiently long moving distance of the moving plate, the necessary twisting amount is increased. On the contrary, if the eccentric dimension is made small, it is necessary to make the pivotal angle of the crank lever large. If the pivotal angle is made large, the lever must be brought to an upright state and as in the preceding case, it cannot be operated through a vertical motion by a robot or the like. In addition, if there is an obstacle above the socket body, the actuating operation becomes difficult.
The present invention has been accomplished in order to overcome the above-mentioned problems.